As a money quote, it doesn't betray much—just typical, guarded coachspeak meant to keep the prying press at bay.

The problem could have something to do with Bolt's right hamstring, a muscle he was seen stretching at length after his second loss to Blake at Jamaican Trials. As is the nature of these things, we'll likely never know the exact cause.

But even if Bolt's hamstring isn't the culprit, his injury withdrawal fits into a troubling, albeit uneven, regression that began with his false-start disqualification in the 100 at the 2011 Worlds and continued with a sluggish performance earlier this year in Ostrava, Czech Republic.

Bolt regained some mojo with back-to-back scintillating performances in Rome and Oslo about a month ago, but his letdown at Trials combined with the latest injury news re-opens the debate over his fitness.

When Bolt is at his best, he's still the greatest sprinter who ever lived. His world records in the 100 and 200 have never been seriously challenged.

That said, there's now a growing pile of evidence to suggest he won't be at his best come August.